Horizontal multi-stage pump vibration problem
Thread Content
Our factory has a D48-50* 12-stage horizontal multi-stage centrifugal pump, medium: Amine liquid working temperature: 80℃ outlet pressure: 6.0MPa inlet pressure: 0.7MPa Due to the abnormal operation of the pump body a few days ago, after disassembly, it was found that the guide vane was corroded by the amine liquid and could no longer be used, so a new stainless steel guide vane was replaced. The outer surface of the first-stage closed impeller rubbed against the guide vane. The impeller material was stainless steel. The first-stage impeller, guide vane, and balance plate machine envelope bearing were replaced. The pump shaft runout was measured (less than 4 wires) and the shaft, impeller, and balance plate were dynamically balanced as a whole. After the assembly is completed and the test machine is completed, the vibration at the front and rear bearings when the outlet is not opened is 2.2㎜/s-3.0㎜/s. After the outlet is opened, the vibration of the non-driving end bearing gradually increases. After the outlet is fully opened, the vibration of the driving end bearing is 7.6㎜/s, and the non-driving end is about 15-18㎜/s. 1. The inlet pipeline is no longer stressed, and the bolts of the outlet pipeline and the pump connection hole can pass directly through it. 2. The backrest wheel connection method is an elastic pin. Use a vernier caliper on the end face of the alignment method, about 10 steps left and right, up and down, and a radial dial indicator for alignment. The error is also about 10 steps. 3. When installing the pump, use a level to be basically level in the transverse and longitudinal directions. The anchor bolts are not loose and are firmly seated with the base. 4. The single-side clearance between the guide vane ring and the impeller hub is 50-60. After the lower part of the outlet gate valve was supported without stress on site, it was found that the vibration of the pump changed greatly after leaving the ground. The driving end became 3.5㎜/s and the non-driving end became 10-12㎜/s. Once the lower part of the outlet gate valve was supported to bear force, the vibration of the pump increased overall. The vibration at the elbow of the pump outlet pipe was 13-15㎜/s, and the inlet pipe vibrated. 3.2㎜/s, two supports are added in front of the outlet check valve, but the vibration value is the highest at these two parts. Now it is suspected that it is caused by the resonance between the pump outlet and the pipeline, but I don’t know how to eliminate this resonance. One of the two supports is fixed to the ground near the elbow and the other is sitting on the ground. Can any master give a possible reason?
According to your description, the possible causes of pump vibration problems are as follows:: 1. Poor coordination between the impeller and guide vanes may cause friction and vibration problems. You replaced the stainless steel guide vanes and impeller, but you may still have a poor fit. It is recommended to check whether the impeller and guide vane are assembled correctly and whether there is any gap or tightness. 2. Pump installation problems, including foundation and pipeline problems. You have confirmed the installation of the foundation and delivery pipelines, but you need to further confirm whether the connection between the pump and the pipelines is firm and whether there is any vibration noise. 3. There may be resonance problems. You suspect that it is caused by resonance between the pump outlet and the pipeline. You need to find out which parts are causing the resonance and try to take measures to prevent the resonance from happening. It is recommended to conduct modal analysis and conduct frequency tuning tests. You can consider adding attenuators or dampers to the pipeline to solve the problem. 4. The axis line of the pump is not perpendicular to the horizontal plane, which may cause vibration of the pump. It is recommended to check whether the installation position of the bearing seat and bearing is perpendicular to the ground, and whether there is any inclination or parallelism deviation. In short, it is necessary to further check the installation and operation of the pump in detail to eliminate various factors that cause vibration problems. .
It should be accompanied by on-site pictures, and whether the process control indicators of the equipment are consistent with the control parameters specified by the equipment itself. From the above description, the installation data meets the requirements. If everything is normal, you have to find the cause from the process to see if it meets the process requirements. It is worth noting whether the above data are consistent with the standards ； Why is the new management changed? ； There has been friction damage to the rotor. Check the volute to see if there is any damage. ； Are the anchor bolts truly locked? There are special cases where, although the bolts are tightened, there is no effective stress link between the equipment and the foundation. . . . . . For reference.
There may be a problem with the materials of the impeller or guide vane ring. The stainless steel ring will be a little sticky.
This post was last edited by Piao Yao on 2023-6-2 22:08 The newly modified pipe is the first time to install the pump, and a certain amount of force is used to bring the screw on.
The problem lies in the forced connection. If the pipe is modified later, the final docking position should be set at the welding joint to minimize the installation stress. In addition, the foundation should be poured with concrete. The solidity of such a foundation is very poor, for reference.